To take a decision for investing in the project is a very crucial part, you have to properly analyze every aspect of the project specially whitepaper & do research about their team members background, experience through different social platforms like LinkedIn. The team is very important as they are going to enhance/build the project in future & so they should be capable to handle the project & won't going to stop working on the project after collecting the funds through ICO & make sure they won't scam. Once you are researching the project you also should check if their source code is available on GitHub or not & their blockchain explorer is running or not. It's up to every investor how much time they take to research & make a final decision to invest in the project or not, as every person is having a different set of mind.